1. Field of the Invention
The present invention relates to a silicone rubber composition filled highly with a silica which is excellent in plasticity and shelf stability, which is made possible by the use of a novel wetter.
2. Description of the Prior Art
It is known that when a silicone polymer is blended with a large amount of a silica filler, the resulting composition becomes excellent in physical properties such as tensile strength, tear strength, elongation, and heat resistance. To blend a large amount of a silica filler into a silicone rubber composition, a wetter also must be blended in a large amount. Conventionally, as a wetter, there is known a low-molecular weight organopolysiloxane having silanol groups at its both ends (e.g., hexamethyltrisiloxane-1,5-diol disclosed in Japanese Patent Publication (kokoku) No. 58-53021 (1983)).
However, the silicone rubber composition wherein the above wetter is used in a large amount is low in plasticity and the surface gives inevitably a tacky feeling. If the used amount is decreased to a certain extent, the crepe hardening of the obtained composition becomes high and therefore the rollability and the extrudability become poor. Further, the wetter has a drawback that the shelf stability is poor because the reactivity of the silanol group in the molecule is high.